Next time you're stuck for a subject line, just refer to this handy reference guide:
The Big Benefit: You already know to emphasize benefits over features, but are you placing your biggest benefit in your subject lines? Try it and if the benefit matches a major desire of your list, you'll likely see your open rate go through the roof.
How-to: This one is easy and effective – use your subject line to indicate you're going to reveal how to do something they are likely to want to do. “How to lose 5 pounds today,” “How to make $100 this afternoon,” etc.
The Urgency Factor: Create some anxiety and get your email opened. You can do this two different ways – first by showing them what they gain by taking immediate action, such as gaining a free Kindle book today only. Second by demonstrating what they lose if they don't act, such as losing entry into a program that is closing shortly.
The Numbered List: There is something almost magical about using numbers in subject lines and headlines, plus it gives you a road map to write the content that follows. For example: “Top 10 reasons why you're doing email marketing all wrong” or “5 ways to get your children to behave.”
Keyword Bait: If you've built a targeted list, then there are certain keywords that will likely get your emails opened by that list. For example, if your list is made up of horse lovers, then you're going to want words like horse, colt, foal, mare, riding etc. in most of your emails since they act as triggers for your readers.
Discover Astounding Secrets: Benefits plus curiosity are always a winner. Use words such as discover, secrets, amazing, astonishing, etc.
Ask a question: A question irresistibly compels the reader to think and answer. “Is he the right man for you?” “Would personal coaching help you achieve your goals?”
The Eyebrow Raiser: If you can get them intrigued enough to raise an eyebrow, they will open your email. For example: “Why chickens are master gardeners,” “The couch potato's guide to weight loss” and “5 foods that make you LOSE weight.”
The Story Starter: Everybody loves a good story, so if your subject line sounds like it's leading into a story, people will click it. “This morning my son asked me where babies come from” and “My client was hopping mad.”
The Curiosity Raiser: You're not telling them much of anything in the subject line, yet you still make them curious enough to open it. How? By raising their curiosity. “This is B.S.,” “Never again,” “What was I thinking?,” etc.